Most available erotic stimulators use vibration and/or a rotary motion to stimulate the user. These erotic stimulators are available in a large variety of shapes and sizes, and share several disadvantages:
the vibration and/or motion, characterized by low force and high frequency, is very different from the physical contact they are meant to simulate;
they must normally be held in place manually by the user so that the vibration and/or motion is transmitted to erogenous areas of the user's body; and
the vibration and/or motion creates considerable noise.
In particular, these disadvantages make existing sexual stimulators unsuitable for use during sleep. A user may wish to utilize stimulation during sleep so as to achieve erotic dreams, as referenced in patent application WO2011132142 A1. However, the noise of vibrating motors typically used in ordinary erotic stimulators is easily transmitted and amplified through a mattress, and is sufficient to awaken the user.
Two existing types of self-stimulation devices that do not utilize motors (and therefore do not produce noise) are the Fleshlight® and inflatable dolls.
The Fleshlight® is an erotic stimulator with a handle and a soft silicone interior. The silicone interior has a hole in which the penis is inserted. This product aims to provide more realistic stimulation than a vibrating device, and it does not produce noise. However, it is a device requiring the user to actively hold and move the device to deliver the stimulation. Further, it can only be used if the user's penis is erect, and the user is awake.
Inflatable dolls (also known as sex dolls, love dolls, or blow up dolls) have the many of the same limitations as the Fleshlight® because essentially they are a Fleshlight® with an attached body, and so require active and intentional movements from the user to derive stimulation from the device.